Retractable landing gear



' Feb. 22, 1938. I R L, LEVY 2,109,427

RETRACTABLE LANDING GEAR Filed Jan. 9, 1936 2 Sheets-Sheet 1 Feb. 22,1938. R. L. LEVY RETRACTABLE LANDING GEAR 2, Sheets-Sheet 2 Filed Jan. 9, 1936 Patented Feb. 22, 1938 UNITED STATES PATENT OFFICE to Socit dlnventions Aronautiques et Meaniques S. I. A. M., Fribourg, Switzerland Application January 9, 1936, Serial No. 58,396

In France January l2, 1935 1 Claim.

invention relates to means for retracting the landinggear of areoplanes,'or the floats o'f hydroplanes, the embodiment of which considerably simplifies known constructions by renderingof a single directing bar of constant length, pivoted at said definite and material points. The 20 definite pivotal point of the direction bar is determined as a function of the relative dimensions of the members of the supporting leg and the retracted position of the wheel, so that, on the wheel being displaced by any means whatsoever,

25 said wheel passes automatically from the lowered to the retracted position, and vice versa,,while the locking of the wheel in the lowered positionwhereby by means of the lifting member itself, or

by any other means-is suflicient to make the en- 30 tire systeni rigid.

- 'In the accompanying drawings:

Figures 1 to 3 are diagrammatic views of known constructionsof retracting means for aeroplane landing gear;

Figure 4- is a side elevation, and

- Fig. 5' is a front elevation of a retractable landing gear in accordance with the present invention;

Figs. 6 and 7 are views corresponding with Figs. 4 and 5 of a modification of the invention,

Referring to the drawings in detail: In the case of machines with two or more engines, the general practice for retracting the landing gear is to employ systems of the type represented in Figure 1, in which the unit, formed by the wheel I, and'supporting fork or leg Lturns on a pivotal axis 3 so as to raise the wheel to a' position 4, in which it is housed in the wing 5, or in the nacelle of the engine.

This solution often has the inconvenience of bringing the raised wheel into a position which is too far rearward in relation to the axis 3, whereas it is desirable-for example, in order to avoid or lessen changes set up in the centre of gravity 55 of the areoplane by the retraction of the wheel-1 is pivoted to the aeroplane at II and the piston to house the wheel in a position 4a, asnearas possible to the axis 3 about which it is raised.

This retracted position 40, of the wheel, in the immediate vicinity of said axis, also has the advantage of lodging the wheel between the longitudinal booms (not shown) of the wing or, more generally, at the point most compatible with the type of construction employed for the aeroplane.-

It is also knownin order to enable the wheel or its equivalent to be raised as close to the axis 10 3 as possible-to provide a hinge 6, see Figure 2, on the supporting leg 2, in such a manner that the 'said leg, or its equivalent, can fold, as indicated in Figure 3, so as to bring the wheel into the most suitable position. I 5

These systems, however, leave open two degrees of freedom to the lifting movement of the wheel I, and consequently allow it to move, not along one curve, but through a series of curves, so that, in order that the raising can proceed along a def- 2o init path, it is necessary to provide a plurality of control members, resulting in complicated, heavy and expensive construction.

Moreover, when the landing gear is in the lowered position, it is necessary, in these systems, to ensure rigidity at the hinge of the supporting leg, by auxiliary means, such as hydraulic, mechanical or other locking devices.

Referring to Figures-4 and 5, wherein the present invention is illustrated, a wheel I is carried by a leg 2, composed of two members hinged together at a point 6. The lower member, below the hinge 6, consists, for example, of a shock absorber, whilst the upper member is adapted to turn on a fixed pivot 3, the whole of this arrangement being, as already mentioned, known per se.

According to the invention, a material point I on the member 2 is compelled to remain at a constant distance from a definite point 8 on the aeroplane, for example, by means of a directing 40 bar 9. Under these conditions the deformation I of the system, so as to bring the wheel from the lowered position I to the raised position lb, Proceeds in a perfectly definite manner, the position assumed by the various members, on being raised, being shown, in Figure 4, by broken lines and the reference numerals of sail members being differentiated by the index character b, the hinge 8 moving to theposition 6b.

Moreover, this deformation may be effected by asingle control effort, suitably directed and applied at a point on the wheel I or the supporting leg 2, for example by means of a jack III, which lower member of the In the embodiment of the invention shown in Figures 6 -and '7, the above described combination of the members is again present, especially the directing bar 9 connecting a material point '1 on the supportingleg with a definite point 8 on the aeroplane.

In this example, the lifting jack l3 which, on the one hand, is pivoted at a fixed point l4, acts, on the other hand, on ahinge l5 provided on an auxiliary leg l6|6, instead of acting direct ly on the supporting leg 2.

As in the preceding example, the action of the lifting jack I3 is sufilcient in itself-by opening the hinge l5-to bring the deformable system progressively into the position in which, by the action of the bar 9, the wheel is completely retracted, viz. l b.

As before, the reference numerals of the various members of the system, when in the raised position, are distinguished by the index character alent, with the axis about which the lifting takesplace, and being constituted by an elastic device,

fork, or any other device.

What I claim as my invention secure by Letters Patent is:-

Retractable landing gear for aeroplanes comprising, for a wheel, a supporting frame, a fixed pivot pin for this frame, a knee joint at one point of this frame, a control bar pivoting about a fixed point of the aeroplane and pivoted, on the other hand, on the supporting frame at a point situated between the wheel and the point of articulation of said frame, an auxiliary leg pivoted, on the one hand, on the aeroplane and, on the other hand, on the supporting frame, and a lifting device pivoted, on the one hand, on the aeroplane and desire to and, on the other hand, on said auxiliary leg.

RENE LUCIEN navy. 

